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PSEUDOMYRMEX APACHE, A NEW SPECIES FROM THE SOUTHWESTERN UNITED STATES (HYMENOPTERA FORMICIDAE) :BY WILLIt.lI S. CREIGHTON Department of Biology, Coll.ege of the City of New York The majority of the material on which this paper is based was secured during 1951 and 1952. At that time the writer was engaged in a field survey of the ants of the border region. This work was made possible by a fellowship from the John Simon Guggenheim Memorial Foundation. My sincere thanks go to the Foundation for the support which made this work possible. The tax.onomy of the genus Pseudomyrmex presents an unusual number of difficulties. Ewen the generic name has not escaped the hazard of uncertainty. The name Pseudo- myrma, which has been accepted for more than a century, has recently been challeng.ed. Twice in the past two years Dr. M. R. Smith has introduced prior names for the. genus. The latest choice is Pseudomyrmex Lund which, .on the basis of data presented by Dr. Smith in 1952 (Proc. Ent. Soc. Wash., Vol. 54, No. 2, p. 97) has a prio,rity of thirteen years over Pseudomyrma Gurin. But any difficulty with the generic name is a minor matter in contrast to the de- pl.orable incertitude which marks a large number of the species in this genus. The taxonomy of many of them is in such confusion that specific recognition is larg.ely a matter of guess-work. With this fact in mind, the writer has hesitated for some time to describe the material treated here. It would seem, how.ever, that we can no longer avoid dealing with this material for, whatever its taxonomic status may be, it is certain that its presence in the south- w.estern United States has not previously been recognized. It is probable that the older records for this ant have been attributed to Ps. pallida. The two insects are superficially Published with a grant from the Museum of Comparative Zoology at Harvard College. 131 132 Psyche [December similar and they occur in the same stations in the southwest. As long as it was believed that only pallida oc'curred in this area, there wa.s little reason to suspect the existence of a second species. The writer first encountered Ps. apache in 1932. In Sep- tember of that year a single, depilated female was taken in Ramsey Canyon in the Huachuca Mountains of Arizona. This insect had a .clear, yellow color similar to that of Ps. pallida, but it differed from the female of pallida in its much greater size and in a number of other structural features. Since no workers were associated with the above emale, its status was problematical and it was not included in my 1950 monograph on North American ants. In the spring of 19.49, after that paper had gone to press, Dr. L. F. Byars sent me a number of w.orkers of a large, yellow Pseudomyrmex which had come from three colonies taken in southern Arizona. These seemed to be the same spec'ies as the female from Ramsey Canyon, but this was not veri- fied until the following summer. In 1950 a colony conta'in- ing all three castes was taken by the writer in Garden Canyon in the Huachuca Mountains. Since that time the writer has secured forty-five additional .colonies of this ant in fifteen different stations. These stations extend from the Brownsville ar.ea of Texas to the mountains of southern California. It is clear that th'is ant is abundant in the southwestern United States and some cognizance must be taken of it. The difficulty is to decide how this insect should be treated. The writer first believed that this ant represented Ps. decipiens or a northern race of it. Dr. W. M. Wheeler had identified as decipiens a series of specimens taken in Costa Rica. These specimens were similar to those coming from the southwestern United States but there were several dif- ferences, particularly in the shape of the petiole. In 1949, when the above comparison was made, there was not enough material to evaluate these differences. As a result the writer told Dr. Byars that the insect probably represented some form of decipiens, but that no certain statement could be made until more data was available. In the meantime the writer attempted to discover how Dr. Wheeler had identi- 1952] Creighto- Pseudomyrmex apache 133 fled the Costa Rica specimens. As far as could be ascer- tained there are no types of decipiens in American collec- tio.ns. Nor do there seem to be any specimens other than types, which Forel might have determined. Apparently Dr. Wheeler used Forel's description as the basis for his identification and, as will be shown, this is a bad business at best. The original description of decipiens appeared in the ant section of the Biologia Centrali-Americana. It was based upon specimens coming from Teapa, a small town in the state of Tabasco, Mexico. The description is brief, but this is not the worst than can be said for it. It is suffi- ciently explicit to show that it does not accord in several important respects with the figure which is supposed to accompany it. These differences are so marked that there is justification for the view that the description and the figure can scarcely have been drawn rom the same insect. In the figure the size of the eyes, the length o.f the antennal scapes and the proportions of the petiolar joints, do not correspond at all to the description. Forel did not prepare the figure but he undoubtedly wrote the description, hence the. latter seems more reliable as an indication of the characteristics of decipiens. Wheeler had evidently reached this conclusion, for his Costa Rica specimens agree much better with Forel's description than with his figure. But it should be clear that there can be no certainty as to the exact nature of Fo.rel's decipiens un,til the types can be re-examined. At the same time it seemed to the writer that it should be, possible to, clarify the status of specimens coming rom the southwestern United States by collecting in northern Mexico. If the southwestern specimens were a northern race ,of decipiens, the two should intergrade at some point between Tabasco and the southern border o,f the United States. The survey work mentioned above gave an ideal opportunity to test this in the field. During January and February of 1952 ,careful vertical surveys were made in the mountains of eastern Mexico at three latitudes. The southernmost of these was in the Tamazunchale area. This survey ranged from three hundred feet to eight thousand f,eet. Similar studies were made in the mountains west of 134 Psyche [December Linares (1300-620.0 feet) and in those south and wes,,t of Monterrey (2000-7200 feet). By this time it was apparent that Ps. apache prefers to nest in old live oak limbs. Many hundred limbs of live oaks were examined in the areas mentioned above. While three different species of Pseudo- myrmex were encountered in these limbs, none of them showed the slightest relation to apache. The coastal plain was less thor,oughly studied, but collections made in the area between Mante and Tampico showed n.o tr.ace of apache. The only abundant Pseudomyrmex in that area is a particularly vicious, light brown species which lives in the thorns of the bull-horn Acacia. In northwestern Mexico the situ.ati,on is essentially similar. Ps. apache is abundant in the mountains at the northern end of the main chain of the Sierra Madre Occidental. But the writer failed to find it in several lesser ranges in northern Sonora. It may be added that in some of these ranges the conditions seemed ideal for this ant and the writer felt certain that it would be found. Negative evidence of this sort does not prove the absence of Ps. apache in the areas mentioned above, but it, does prove that the insect is less abundant in these areas than in stations further north. This would not be true if this ant were a northern fringe f some southern species, for in that case its incidence should increase to the south. Bu, since all available evidence points to. the fact that the area of greatest abundance for this ant lies in southern Arizona and that its incidence decreases to the south, i is safe to conclude that the insect is not a northern race of decipiens but a separate species. Since all three castes have been figured on the plate which accompanies this article, the descriptive material vchich follows is largely limited to details of sculpture and pil,o,sity that could n,t be shown in the figures. Pseudomyrmex apache sp. nov. Plate 12 Femal,e: head (mandibles excluded) 1.35 mm. thorax 2.2 mm. overall length 7-8 mm. Upper surface of the head covered with small, shallow, circular punctures. These punctures close set from the anterior margin of the head to the level of the median ocel- 195.] Creighton--- Pseudomyrmex apache 135 lus. From that level to the occipital border the punctures are much more widely spaced with the surface between them delicately coriaceous or reticulate and very feebly shining. The punctures on the genae and gula ar.e notably sma'ller and more widely spaced than those on the front of the head. Both genae and gula are feebly shining. Clypeus and frontal lobes without distinct punctures and rather strongly shining.

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